Device for forming grinding wheels



19, 9 F. G. KRAFFT 2,586,235

DEVICE FOR FORMING GRINDING WHEELS Filed Sept. 8, 1947 2 SHEETSSHEET l INVENTOR FREDERICK G- KRRFFT fat... 6 mm- ATTORNEY Feb. 19, 1952 F. G. KRAFFT 2,586,235

DEVICE FOR FORMING GRINDING WHEELS Filed Sept. 8, 1947 2 SHEETS-SHEET 2 INVENTOR FREDERICK 6. KRHF'FT ATTORNEY Patented Feb. 19, 1952 UNITED sTATEs PATENT OFFICE ,2 Claims. (01. 51-5 This invention relates to grinding machines and equipment therefor, and particularlyto an improved arrangement for dressing a grinding wheel by a crushing roll and for forming the crushing roll.

In grinding operations on workpieces such as chasing tools for die heads and the like, the manufacturer must produce a great variety of pitches, the most popular sizes being from 6 pitch to 56 pitch. Many other sizes, both standard and special, are also manufactured.

The technique of crush forming a grinding wheel by a crushing roll is particularly adapted for this type of production, but the usual methods of producing rolls, especially in the quantity and variety necessary for this type of production, require the investment of a great deal of capital in rolls or roll grinding machines.

The object of the present invention is to provide an arrangement for producing rolls of the type referred to above in such a manner that the cost of the rolls is greatly reduced.

Another object is to provide an arrangement wherein a roll of any predetermined type can be formed in the fixture in which it is to be used to form the grinding wheel.

Still another object is to provide an arrangement for forming grinding wheel crushing rolls at low cost and in which arrangement the roll forming apparatus is a very inexpensive arrangement.

These and other objects and advantages will become more apparent upon reference to the following description taken in connection with the accompanying drawings in which:

Figure 1 is a partial side elevation of a grinding machine having mounted thereon a dressing fixture and roll forming apparatus according to this invention;

Figure 2 is a plan view over the table of the machine shown in Figure 1 showing the dressing and roll forming fixture more in detail;

Figure 3 is a fragmentary perspective view showing one form of shaving tool adapted for use in connection with the fixture shown in Figures 1 and 2;

Figure 4. is a vertical section through a part of the roll forming fixture and is indicated by the line 4--4 on Figure 1;

Figure 5 is a sectional view indicated by the line 5-5 on Figure 2 and shows a shaving mechanism employed in connection with the crushing roll; and

Figure 6 is a section indicated by the line 6 on Figure 5 and showing the clutch mechanism of Figure 5 more in detail.

Referring to the drawings, Figure 1 shows va grinding machine having a bed ID on which is reciprocably mounted a table l2. The table is adapted for receiving a workpiece supporting fixture l4 on which is mounted the be ground l6.

Secured to the bed It] or rigidly mounted adjacent thereto is a column l8 which receives a saddle 20 for vertical reciprocation. Carried in the saddle 20 for transverse reciprocation therein is a wheel head 22 on which is mounteda grinding wheel as on the shaft 26.

-The saddle may be adjusted vertically on the column l8 by any suitable mechanism such as by the lead screw and nut indicated at 28, the lead screw of which is adapted for actuation by the hand wheel 30 and the bevel gearing 32.

Mounted at one end of the table I2 is a fixture comprising a first frame part 34 which is stationary on said table and which has journaled therein a shaft 36 on which is mounted the crushing roll 38. Slidably mounted on the frame 34 is a second frame 40 which has journaled therein a shaft 42 which mounts a turret 44. The second frame 40 is guided on the first frame 34 as by the means of the dovetail slide shown at 46 in Figure 4, and is adjustable toward and away from the axis of the shaft 36 by the screw 48 and hand wheel 50 carried on the first frame and screw threadedly engaging the second frame.

Reference to Figures 2 and 4 will show that the turret structure 44 comprises a block 52 which has a plurality of slots 54 therein and in which are mounted the shaving tools 56. The tools 56 are locked in position by any suitable means, such as the set screws indicated at 58.

As will be seen in Figure l, the shaving tools are adapted for being presented to the roll 38 substantially on the horizontal center line thereof. For selectively indexing the block 52 to bring the shaving tools selectively into position relative to the crushing roll, the shaft 42 carries an arm 60 having a plunger 62 therein the end of which is adapted for entering the holes 64 in the upstanding side plate of the frame 40 in which the shaft 42 is journaled. The block 52 is keyed as at 66 to the shaft 42 and the indexing of the shaft thereby insures that the block 52 will also be indexed through the same angular movement.

The dressing roll 38 must be driven during the time it is being shaved and to this end is keyed as at 68 to the shaft 36. The shaft 36 is then connected through the, overrunning clutch mechanism 10 to the worm wheel 12 which is driven by the worm 14 on the shaft 16 which is driven by the gear head motor 18 mounted on the frame 34.

Usually, the crushing roll idles when the wheel is being crushed thereby, and the wheel is driven at low speed in order to provide for the rolling action of the wheel and roll. To this end the overrunning clutch mechanism at 10, best illustrated in Figure 6, permits the roll workpiece to '3 to idle in one direction of movement relative to the worm wheel 72. As shown, the worm wheel '12 is connected with the cage 16 of the clutch which has a plurality of spiral shaped grooves 18 therein. Connected with the shaft 36 is the cylindrical block 86 and positioned around the block are the balls 82 which lie within the grooves 78. It will be seen that clockwise rotation of the block 19 in Figure 6 will cause the balls 82 to wedge in the slot 18 and thereby to drive the shaft 36. On the other hand, if the cage 16 is held stationary; then the shaft 36 is free to rotate.

The shaving tools indicated at 56 may have any configuration along the edge thereof but for. the purposes of illustration are shown as bearing V threads. A representative tool of this type is illustrated in Figure 3 andit will be seen that the tool can be restored to the original sharpness at any time by grinding off a predetermined amount thereof as indicated at 84 across the working edges of the teeth.

In operation, a blank roll is mounted on the shaft 35. The turret mechanism M is then indexed to bring the proper tool into shaving alignment with the blank roll. Thereafter the screw 48 is actuated to bring the shaving tool into engagement with the blank roll. At that time the motor '58 is energized to drive the roll at shaving speed. By forcing the tool against the roll the periphery of the roll will be shaved to the proper configuration. Thereafter the shaving tool is retracted from the roll and the wheel 24 is brought into crushing "engagement with the roll. After the wheel has been dressed to shape it may be employed for grinding workpieces which will have the same cross-sectional configuration across their ground surface as the crushing roll which was employed for shaping the grinding wheel.

At any time the roll becomes worn beyond the tolerance limits, the proper shavin tool may be reengaged therewith to true the roll surface. After a predetermined number of shaving cycles, the shaving tool may become somewhat worn and it may be restored by grinding it as shown ates in Figure 3.

The turret mechanism has been shown in the drawings as being adapted for receiving four tools but it will be understood that any number of tools could be mounted therein that it was desiredto employ. Since each shaving tool is of a different configuration, or, as shown, of a different pitch, then as many forms can be ground on the machine as there are tools in the turret structure. This greatly simplifies the production of several varieties of workpieces because it is only necesary to replace the crushing roll, and sometimes the grinding Wheel, in order to prepare for a new work cycle.

The rolls are inexpensively produced from blanks and once formed can be employed for a considerable length of time. As rolls are usu ally formed on a cylindrical grinder, or purchased irom a manufacturer thereof, it will be evident that the arrangement of this invention offers a substantial saving in the cost of the rolls and in the investment necessary in equipment for forming the rolls.

It will be understood that this invention is susceptible to modification in Order to adopt it to different usages and conditions and, accordingly, it is desired to comprehend such modifications within this invention asmay fall within the scope of the appended claims.

I claim:

1. In a grinding wheel dressing device; a first frame; a second frame slidably mounted in said first frame; a roller jo'urhaled in one of said frames with the surface form of the roller in true radial alignment with the complementary surface of a grinding wheel said grinding wheel and roller being relatively movable for contact therebetween; a turret journaled in said second frame; a plurality of shaving tools mounted in said turret angularly spaced and each adapted to engage the roller over its entire width and spaced around the periphery thereof having the complementary configuration in radial alignment with the surface form of said crushing roll; angularly spaced recesses in one side of said second frame; means fixed to said turret for turning therewith and receivable in said recesses whereby the turret may be selectively indexed; and motor means mounted on said secand frame and connected to said roller for driving said roller during the shaving thereof.

2. In combination in a grinding machine; a reciprocable table; a grinding wheel for grinding workpieces mounted on said table; a fixture on said table comprising a stationary frame and a frame slidable thereon; a roller journaled in said stationary frame with the surface form of the roller in true radial alignment with the complementary surface of a grinding wheel said grinding wheel and roller being relatively movable for contact therebetween; a turret journaled in said slidable frame upon an axis parallel to said roller; a plurality of shaving tools mounted in said turret angularly spaced and each adapted to engage the roller over its entire width and spaced around the periphery thereof having the complementary configuration in radial alignment with the surface form of said crushing roll; angularly spaced recesses in one side of said second frame; means fixed to said turret for turning therewith and receivable in said recesses wherebythe turret may be selectively indexed; means mounted on said stationary frame and connected to said roller for driving said roller in one direction during the shaving thereof; and means freeing said roller from connection to said driving means whereby the freed wheel is independently rotated in the same direction during the dressing of said wheel thereby.

FREDERICK G. KRAFFT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 469,377 Richards Feb. 23, 1892 553,802 Bardons et a1. Jan. 28, 1896 740,107 Dworzek Sept. 29, 1903 787,582 Maloney Apr. 18, 1905 999,841 Nelson Aug. 8, 1911 1,216,060 Breeden Feb. 13, 1917 1,249,758 Hey -1 Dec. 11, 1917 1,698,807 Willhauck Jan. 15, 1929 1,896,533 Vuilleumier Feb. 7, 1933 2,436,527 Polk et a1 Feb. 24, 1948 FOREIGN PATENTS Number Countr Date 130,879 Germany May 22, 1902 486,332 Great Britain June2, 1938 645,834 France Jim; 3, 1928 

